1. Field of the Invention
This invention relates to the techniques for manufacturing field-emission type electron emitters, and more particularly to a method of manufacturing field-emission type electron emitters which has improved a conductive activation process, and further, to a method of manufacturing substrates on which a matrix electron emitter array with field-emission type electron emitters arranged in a matrix has been formed.
2. Description of the Related Art
In recent years, an electron beam excitation fluorescent display unit using surface conduction emitters, that is, field-emission type electron emitters, has been attracting attention as a large-screen and thin display. This display unit has the following various merits: the surface conduction emitters are formed using printing techniques; the same principle of light ray emission as that of the cathode-ray tube is used because of the fluorescent material excitation light ray emission caused by electrons; and low-breakdown voltage driving ICs can be used because the surface conduction emitters can be driven at a voltage of a little higher than ten volts.
The basic configuration, manufacturing method, and driving method have been described in detail in reference (E. Yamaguchi, et. al., xe2x80x9cA 10-in. SCE-emitter display,xe2x80x9d Journal of SID, Vol. 5, p. 345, 1997).
A method of manufacturing surface conduction emitters of this type has been disclosed in, for example, Jpn. Pat. Appln. KOKAI Publication No. 2000-331599. In this method, a pair of electrode patterns is formed on a substrate and a conductive thin film is formed between these electrode patterns. Then, the conductive thin film is subjected to a conducting process, thereby carrying out a forming process, with the result that electron emitters are formed. Specifically, a triangular pulse voltage is applied to a pair of electrodes. When the voltage is raised gradually, part of the conductive thin film breaks, deforms, or deteriorates, with the result that it is changed into a structure suitable for electron emission. The forming process is completed when the low triangular voltage pulse current, which is being monitored, becomes sufficiently small. Through this process, an electron emitting section for emitting electrons is formed at the conductive thin film.
To increase the electron emitting capability, the aforementioned conductive activation process is carried out under vacuum. Specifically, in an atmosphere of organic material, a pulse voltage as shown in FIG. 1A is applied between electrode E1 and electrode E2 forming a pair constituting a surface conduction emitter schematically shown in FIG. 1B, thereby forming an electron emitting section formed in the forming process and a thin film made of carbon and carbon compounds near the emitting section. The element current flowing between the two electrodes during conductive activation is increased gradually and saturated. When the current is saturated, the surface conduction emitter is completed.
Although a single surface conduction emitter has been explained for the sake of simplicity in FIG. 1B, a display unit has a large number of surface conduction emitters arranged in a matrix. In a method of forming electron emitters arranged in a matrix, the electrodes and conductive films are formed by printing, resist application, exposure, etching, and other processes as in ordinary thin-film processes. Since the forming process and activation process require a conducting process, the X and Y row lines and column lines are caused to conduct as shown in FIG. 3. For example, the column lines are connected in common to the ground (GND). The row lines are selected sequentially and a pulse voltage shown in FIG. 1A is applied to them in this order: S1, S2, S3, . . . .
The surface conduction emitters formed in this way are provided so as to face a fluorescent material substrate on which a fluorescent material pattern has been formed. The surface conduction emitters are combined with the fluorescent material substrate to form vacuum cells. The vacuum cells are connected to an external driving circuit, thereby completing a display unit. A display signal voltage is applied to each of the electron emitters, which emit electrons according to the display. As a result, the fluorescent material formed on the opposite substrate is excited, emitting light rays, which displays an image. As described in detail in Jpn. Pat. Appln. KOKAI Publication No. 2000-331599, the driving method is a line sequence method. That is, the voltages corresponding to the display signals are applied to the corresponding electron emitters.
In a fluorescent display unit where the surface conduction emitters are arranged in a matrix, a pulse voltage is applied to the surface conduction emitter corresponding to each pixel by the line sequence method, thereby emitting electrons. At this time, the luminance changes according to the amount of emitted electrons, displaying gradation. Gradation display is achieved by a method of changing the pulse width of the pulse voltage applied to the electron emitters or a method of changing the voltage amplitude of the pulse voltage. At this time, to obtain a good image, it is important that the electron emission characteristic of each surface conduction emitter is the same.
However, in the actually formed surface conduction emitters, their characteristics vary because of variations in the pattern dimensions of the conductive thin film, variations in the thickness of the conductive thin film, and variations in the characteristic of the electron emitting section formed in the forming process. The variations in the characteristics cause the problem of adversely affecting the display characteristics. This is because a sharp rise in the current-voltage characteristic of a surface conduction emitter as shown in FIG. 4 causes a slight difference of the characteristic to make variations in the output current larger.
As described above, in a conventional method of manufacturing field-emission type electron emitters, a conductive thin film is subjected to a conductive activation process, thereby forming an electron emitting section. The activation process, however, is not carried out uniformly all over the electron emitters, which causes the problem of permitting the electron emitters to vary in characteristic. Variations in the characteristics of the electron emitters contribute to the deterioration of display quality when a display unit is constructed.
An object of the present invention is to provide a method of manufacturing field-emission type electron emitters which enables field-emission type electron emitters to be manufactured with high uniformity and helps improve display quality when being applied to a display unit.
Another object of the present invention is to provide a method of manufacturing matrix electron emitter array substrates which decreases variations in the characteristics of the electron emitters remarkably even when using field-emission type electron emitters and enables display quality to be improved.
According to an aspect of the present invention, there is provided a method of manufacturing field-emission type electron emitter unit comprising a plurality of field emission type electron emitters, each of the electron emitters comprising a pair of electrodes formed on an insulating substrate, a conductive thin film formed between the pair of electrodes, and an electron emitting section formed in the conductive thin film, the method comprising:
supplying current to the electron emitters being connected in series for forming the electron emitting sections.
According to another aspect of the present invention, there is provided a method of manufacturing field-emission type electron emitters, comprising:
forming a plurality of pairs of electrodes on an insulating substrate, each of the pairs of electrodes being adjacent;
forming a conductive thin film between the pairs of electrodes; and
forming the electron emitting sections by supplying current to the electron emitters connected in series.
According to still another aspect of the present invention, there is provided a method of manufacturing a matrix electron emitter array substrate comprising an insulating substrate, a plurality of scanning lines which are formed on the insulating substrate to be substantially parallel with each other, a plurality of signal lines which are formed in a direction to cross the scanning lines to be substantially parallel with each other, the signal lines being isolated from the scanning lines, and field emission type electron emitters which are formed in the pixel areas defined by intersections of the scanning lines and the signal lines and which are arranged in a matrix, and each of the field emission type electron emitters comprising a pair of electrodes formed on the insulating substrate, one of the pair of electrodes connected to one of the scanning lines and another of the pair of electrodes connected to one of the signal lines, a conductive thin film formed between the pair of electrodes, and an electron emitting section formed in the conductive thin film, the method comprising:
forming the electron emitting sections by supplying current to the electron emitters connected in series.
According to still another aspect of the present invention, there is provided a method of manufacturing a matrix electron emitter array substrate comprising an insulating substrate,
a plurality of row lines which are formed on the insulating substrate to be substantially parallel with each other, a plurality of column lines which are formed on the insulating substrate to be substantially parallel with each other in a direction to cross the row lines, the column lines isolated from the row lines, field emission type electron emitters which are formed in pixel areas defined by intersections of the row lines and the column lines, the method comprising:
forming pairs of electrodes arranged in a matrix on the insulating substrate, one end of each pair of the electrodes connected to one of the row lines and the other end of each pair of the electrodes connected to one of the column lines,
forming a conductive thin film between the electrodes in each pair; and
supplying current to the electron emitters connected in series to form the electron emitting sections.